Certain identifiable neurons and muscles of the moth Manduca sexta undergo a rapid, developmentally programmed cell death during metamorphosis to the adult. The commitment of these muscles to degenerate requires new RNA and protein synthesis. The present work seeks to identify genes which encode "cell death" specific proteins. Poly A+ RNA will be used to construct stage-specific subtraction cDNA libraries in lambda GT10, and individual recombinants will be screened to confirm that they contain developmentally regulated cDNA sequences. These clones will then be sequenced to determine the primary structure of their presumptive protein products. Comparison of these sequences to those in protein databases may allow us to identify the nature of their function. Clones which appear to meet several defined criteria for cell death genes will be expressed in bacteria or antibody production. Both antibody and nucleic acid probes will be used to begin characterization of the mechanisms involved in regulating cell death during development in Manduca and a related moth species Antheraea polyphemus. The expression of homologous cell death genes will also be examined in frog and chicken using the antibodies and nucleic acid probes from Manduca.